Yeah, if you block email it sends back a message saying the email doesn't exist and the junk mail server removes your name..
I've lowered my junk mail from about 15 a day to 1 or 2 by:
1) Noticing a lot of it came from the same email address, so I blocked the email address - most email clients have a block list
2) Sending a email from the TiBB server to the sender saying that my address didn't exist, and it actually worked
- Mark